This is probably the oddest recommendation I'd ever written on Chowhound - a nameless place, without an address, by a highway thru Pasir Mas district, linking Kota Bharu to the border town of Rantau Panjang (on the Malaysian-Thai border).
The Pasir Mas locals inadvertently know this place as the "Nasi Ulam place by the Pasir Mas Highway". You won't miss it - and I do mean that: on a largely nondescript stretch of road, you won't miss the literally dozens of cars stopped by this ... large shack with corrugated tin roof. Hundreds of local Malays stream in and out of the eatery non-stop during lunch-time.
"Nasi Ulam" is basically a meal which consisted of steamed white rice, which you eat with a choice of side-dishes which can include a variety of fabulous Thai-accented Kelantan-style curries including a very memorable one I have which was made from beef and tendon, fried catfish, deep-fried turmeric-marinated chicken and an assortment of fresh, raw herbs, vegetables and ferns - collectively known as "ulam". During my lunch there, I ate some varieties of leaves and plants which I never *knew* was edible, let alone the fact that they are aromatic and pretty tasty - there were poached mimosa ferns, boiled cashewnut leaves, crisp jungle guava leaves, etc. A strong-tasting, even stronger-smelling dip called "budu" was served with the "ulam". "Budu" is typically Kelantanese - you go anywhere in Malaysia and you say you like "budu" and Malaysians will *know* you are from Kelantan. It is an ultra-strong fermented fish sauce with the color and consistency of grey mud. Its taste is reminiscent of Cambodian "prahok" - not a surprise since the Kelantanese-Malays are descendants of early settlers from the old Champa kingdom of Cambodia in ancient times.
"Budu" at this nasi ulam place come with finely-julienned raw mango and chopped chillies, given a sourish tinge with squeeze of local fresh lime ("limau kasturi"). I absolutely loved it!